In the period 25-27 September 2023, the international XShootU workshop (https://stelweb.asu.cas.cz/xshootu/) was held in Prague in Vila Lanna, attended by 45 participants from all over the world. XShootU is an open collaboration of astrophysicists working on various scientific aspects arising from the ULLYSES program and the corresponding XSHOOTER data on massive stars. ULLYSES (UV Legacy Library of Young Stars as Essential Standards) is a large-scale Director’s Discretionary program for the Hubble Space Telescope (HST) that devotes approximately 1000 HST flybys to the creation of a spectroscopic ultraviolet (UV) spectral library of high- and low-mass young stars. To supplement the UV data for massive stars brought by ULLYSES, the organizing committee of the IAU Commission G2 (massive stars) successfully submitted a proposal to ESO to obtain complementary spectra in the optical and near-infrared parts of the electromagnetic spectrum. These observations are made using ESO’s XSHOOTER spectrograph. The results obtained based on these observations were presented at the workshop. The main organizer of the workshop was dr. Brankica Kubátová, who is the contact person for the study of structures in the wind of massive stars within XShootU.
